Used to mount and separate electrical power and signalling lines on poles, this clear glass insulator is made up of several parts that give it a distinctive shape: the rounded dome and crown, a wire ridge and groove, skirt, and base.

This clear glass insulator has a top groove and was used to mount and separate electrical power and signalling lines on poles. It has a round base and is embossed with "U.S.A. 4-56 & Kimble - 830 Tempered."